The present invention relates generally to systems and methods of flexible power management, and more specifically, to systems and methods of flexible power management applicable to digital broadcasting.
The research, development, and promotion of digital broadcasting, including digital TV (DTV) broadcasting, have made digital broadcasting a much more popular and acceptable form of broadcast. Replacing the conventional analog channels and programs with their digital renditions is only one of many DTV's intrinsic features. As many other industries, such as internet and mobile communication one trend is to adequately integrate digital broadcasting with other fields and applications of technologies and services. One of those attempts includes using a handheld device to receive and decode digital broadcasting signals, thereby allowing consumers to enjoy digital broadcasting services anywhere and anytime. Such application brings the applications of digital broadcasting to a new level not reached by the conventional devices. Among other efforts, a new Digital Video Broadcasting-Handheld (DVB-H) standard has been proposed.
There are, of course, many differences between receiving a DTV program from a home DTV set and from a personal handheld device. For example, the display of the former is typically of larger size than that of the latter, which also has limited power. Among others, power consumption is an important consideration for handheld devices, because a handheld device gets its power from an energy-limited battery instead of a wall outlet. Therefore, an energy efficient process is required for DTV broadcasting to handheld devices.
Referring to FIG. 1A, in the case of Digital Video Broadcasting-Terrestrial (DVB-T) system, all services (or programs) within one channel are uniformly multiplexed based on capacity division multiplexing (CDM) into a single transport stream (TS), which is then modulated and transmitted. The receiver has to demodulate the received signal all the time even though most viewers usually need only one service at a time. Processing information of all services, particularly the non-selected services, unnecessarily consumes more power. Obviously, receivers in the DVB-T system always suffer from a waste of power due to the above arrangement for steaming.
Referring to FIG. 1B, to reduce the average receiver power consumption, the DVB-H system introduces a scheme based on time division multiplexing (TDM), known as “time-slicing”, for multimedia streaming. For example, DVB-H uses a time-slicing based mechanism to put different services, which may be distinctive DTV programs, at distinctive time slots. Accordingly, a receiver only needs to process the information at and near the intervals where the viewer-selected-service(s) are present. Indeed, the receiver may deactivate most of the processing functions or enter into a “sleeping” mode during most of the remaining intervals. For example, referring to FIG. 1C, the burst duration indicates the duration where a receiver is activated to process the information. During the remaining duration, such as the off-time duration shown in FIG. 1B, most of the signal processing functions may be deactivated to reduce consumption of power. This mechanism has been approved as part of DVB-H's standard. Nevertheless, it should be noted that time-slicing provides the solution of only power saving rather than power management. That is, the problem with DVB-H'H's service-based time-slicing mechanism is a lack of flexibility for power management. Under certain circumstances, the power consumption of processing only one service may still be too much for certain systems. Therefore, there remains a need for systems and methods that provide flexibility in power management.